FI113069B - Pressure selection combination and its manufacturing process - Google Patents

Description

113069

Press roll assembly and method for its manufacture

The present invention relates to improved press rolls, and in particular to improved press rolls and a process for their manufacture, wherein a press roll is induced by radial compression to resist differential thermal expansion of the web body and the metal flanges or ends at its end.

Press rolls, and in particular granite press rolls 10, can be used in paper and board making machines in addition to other uses. Generally, press rolls are held in press roll devices or combinations by means of steel ends or flanges supported by the shafts in a rotatable manner. Mechanical stress and temperature-15 fluctuations under which rolls are used in industrial applications can result in axial cracking, circumferential fracture, or fatigue damage of the granite body.

The most dangerous compression roller damage is due to axial cracking, which is mainly due to the thermal stress in the rock material due to the mouth of the steel ends attached to the ends of the granite roll; for better thermal expansion, granite roll thermal expansion! with a coefficient much lower than that of steel. Thus, the expansion of these steel ends '·' 25 causes circumferential tension in the press rolls. In addition, the probability of serious damage to the press rolls is increased. '* Continuously adjusts in modern ultra high speed machines, where higher temperatures and medium exhaust forces increase roll tension.

* * *; 30 In Vestola et al., "Granite. Rolls - Failures, Their Prevention and Substitute Material, Rials," CCPA Annual Meeting Minutes, Montreal, Canada, * B-109 (1989) show that shaft damage can be avoided. By design, and that circumferential fracture can be reduced by appropriate dimensioning and prestressing. However, there is a need to eliminate the cause of the most dangerous compression damage, axial cracking caused by circumferential or rim tension.

Vestola et al show that granite rolls 5 whose shafts are tightly fitted to the roll hole or whose shafts are surrounded by concrete grouting generally exhibit high rim tension on the inner surface of the granite roll when a rapid temperature rise in the shaft can occur due to friction or mechanical failure. However, when the shaft is not rigidly fitted or the roll is without a glass Titus, Vestola et al. Show that the stress of granite pressing rolls cannot be completely eliminated, based on the principle that differential thermal expansion of metal ends at roll ends circumferential stresses at the ends of the granite roll. Such circumferential tension is believed to be due to the fact that the metal ends expand radially faster than the roll ends because the coefficient of thermal expansion of the steel, which is the material of these metal ends, is higher than that of the roll material (usually granite). ! friction between the granite roll and the roll ends, so that relative (sliding) movement of the end flanges in contact with the roll end surfaces is not possible.

One prior art solution to the radial expansion problem of the press rolls has been to press the roll with its opposite conical male ends secured to compatible female tapered surfaces of the steel ends. Figure 1 shows one end of such a previously known press roll, whereby it will be clear. that the opposite end of the press roll is mainly a mirror image of its other end. A press roll 2 made of granite or other suitable material is aligned axially and centrally about an axis 4 which passes through a hole 6 *. The centering ring 8 ensures that the shaft 4 is radially centered on the roller 2 about its axis of rotation. The press roll 2 ends with a tapered conical surface 10.

The press head 12 is connected to the shaft 4 and includes a ring 14, one part of which is pressed against the tapered male end surface 10 of the press roll 2. The inner surface 16 of the ring 14 comprises a conical surface similar to the tapered male surface 10 and 10 in surface contact therewith, forming a smooth and continuous interface. The axial force applied to the ends compresses the ends against the tapered conical ends of the press roll, providing radial force against the stone and generating radial press force and tension in the press roll.

Compression of the ends before assembly of the press roll device can be accomplished by lengthening the shaft by heating it with respect to the press roll and then cooling the shaft, causing both longitudinal (axial) and radial compression of the press roll. An example of such a method and apparatus is described in Hill, U.S. Patent No. 4,101,123. It is also possible to use one or more!,. * Tie rods, threaded rods or cables instead of the central axis [25 or in addition to provide tension between the opposing press roll heads, see Figs. Muhle et al., U.S. Patent No. 4,642,862. In addition, a fixed roll, ·. · Comprising opposite tapered male ends, can be compressed between two female ends which are compressed relative to the roll by external force.

U.S. Patent No. 4,924,688

Cutmore, and U.S. Patent No. 4,991,275, to Adams Sr., also disclose roller assemblies having rolls with tapered male ends 35 subjected to axial compression by compression 113069 with 4 poles or collars with tapered inner surfaces at a compatible angle with respect to the tapered ends of the roll. These patent documents are incorporated herein by reference.

In the prior art methods, the nature of the compressive forces exerted on the roll is more easily understood by referring again to Figure 1. The longitudinal compression acting on the shaft 4, represented by the power line 18, is converted into a smaller longitudinal component 10 and a radial compression component 22 by a non-straight line between the tapered female end 10 of the press roll 2 and the tapered or bevelled inner surface 16. During heating of a roll having a co-15 compressed tapered male end between opposite tapered or conical female ends, this longitudinal compression component can be reduced by a larger longitudinal expansion of the roll relative to the length of the roll, thereby compensating for this longitudinal extension However, the steel end also expands. ·,: Radially outwards and between the steel end and the roll end! this friction can contribute to the formation of circumferential tension in the roll.

II · 't 25 In addition, the conical ends of the granite roller and their compatible steel ends are difficult to fabricate, particularly with any degree of precision, and •: · difficulty in achieving a smooth interface between the tapered ends of the roll and the tapered steel ends; compression that can cause roll cracking or other shortening. this roll life. In addition, the thermal expansion of the steel ends, internal shaft (if used), and centering rings (if used) causes a stress strain on the 35 press rolls.

113069 5

Difficulties in machining tapered press roll ends and making compatible tapered steel ends creates a need for a method of applying radial compression force to press rolls containing a linear interface between roll ends and steel ends or clamping plates. There is also a need for a press roll where the circumferential stress caused by thermal expansion of the roll ends of the roll, the inner shaft (if used), and the centering ring (if used) are substantially eliminated at the operating temperature of the press roll.

The press roll assembly according to the invention and the process for its manufacture are characterized by what is claimed.

Thus, the main object of the present invention is to manufacture a press roll device which includes a straightforward interface at the interface between the roll ends and the steel ends, which does not exhibit any significant circumferential tension at operating temperature.

It is a further object of the present invention to provide a method for manufacturing a press roller device which includes a linear interface roller and; between the steel ends and with no significant circumferential tension at operating temperature.

These and other objects of the present invention are achieved by a process for manufacturing a press roll device and the resulting press roll combinations using * a higher roll strength material, preferably granite (capable of withstanding: about 25,000). psi maximum compression stress, but only 1,500 psi tensile stress), and radial pre-compression. The steel ends with a higher thermal expansion coefficient than granite are preferably heated to a temperature higher than the roll I 1 and are forced against the roll ends by a longitudinal post-tension of 113069 6 caused by the steel tensioning tendons passing through the holes in the roll. The high reaction force between the steel ends and the roll ends causes a considerable frictional connection between the two elements, whereby the radial expansion or contraction of the steel end does not cause the steel end to slip relative to the granite but instead to exert considerable force on the roll. Thus, the roll is compressed in the radial direction as the steel ends of the cavity cool down.

This radial compression cancels out the tensile, strap, or circumferential stress that is generated on the roll during its use due to the increased thermal expansion of the steel ends due to the roll during use of the device. Thus, the radial compressive force can be applied to the compression cavities which include a planar interface between the roll ends and the steel ends, and thus this radial compressive force is used to compensate or cancel the stress caused by the differential expansion between the roll ends and the steel ends.

The invention will now be described with reference to the following. ; 1, a partial cross-sectional view of the prior art press roll including a roll connected to a female steel end tapered at its tapering male end; and Fig. 2 shows a transverse cross-sectional view of a preferred embodiment of a press roll device made in accordance with the present invention.

Fig. 2 is a cross-sectional view of a preferred embodiment of the present invention which '. comprises a press roll assembly. In this context, check. «'Mainly only one end of the combination, since it is clear that the other end is mainly a mirror image of it. The dismounting roller roll 30 30 is preferably made of granite and includes a plurality of axially parallel bore holes 32 extending outwardly from the axis of roll 30 extending from a radial flat end face 34 to an opposite radial flat end face 5 of roll 30.

The end face 34 of the roll is substantially flat and includes an annular peripheral shoulder 38 on its periphery. The end 40 is preferably made of steel and has a substantially cylindrical hub portion 42. The hub portion 42 is made in a single piece with a cylindrical flange or plate 44 and also includes an axially for support. (Thus, it is desirable to use steel ends having a shaft and flange of the same piece.) The hub portion 42 may be tapered to provide additional support for the plate 44 or to reduce the amount of material used to form the end 40. The reinforcing plate 44 is fixedly connected to the disc 48, the peripheral lip 50 of which is bounded by a cylindrical inward surface 51 and a flat radial surface 53 by the circumference of its periphery. A plurality of bore holes 54 pass through disk 48 and plate 44. The outer surface 52 of the disk 48 is substantially flat and the periphery of the disk 48. ·,: is thermally expanded equal to the circumference of the roll 30 whereby the lip portion 50 of the disk 48 fits inside the peripheral shoulder 38, 25 to form a smooth 34 and the inward faces 51, 52 and 53 'of the disk 48. The lip portion 50 and the shoulder 38 are mainly used to center the * end 40 with respect to the roll end 34. However, their use is not necessary and may be i; 30, so that only smooth roller and steel end mounting surfaces could be used without any drawbacks. Also, no. it is not critical that the diameter of the disk 48 is the same as the diameter of the roll 30. In practice, the disc 48 may be substantially larger or smaller than the roll 30 in diameter 35, and furthermore, a gap may be readily formed between the surface 51 of the lip portion 113069 and the surface 38 of the shoulder 38. The reinforcing plates 44 may also be omitted so that the steel ends comprise only flanges or discs 48 which may be fixedly attached to the shaft or supported by rotation by other conventional techniques.

The roll assembly process begins with heating each end member 40 just below the maximum operating temperature under which the press roll is in use. Temperatures higher than this maximum operating temperature or Mata-10 ponds may also be used, depending on the ultimate stress to which the roll is subjected. It is not necessary to heat the steel ends to a maximum operating temperature to substantially mitigate the circumferential stress caused by the differential thermal expansion at the roll ends as the rolls expand slightly. The steel ends 40 are then positioned at the ends of the roll 30 and the tendons or other conventional tensioning devices are placed in the holes 32, 54 and tightened to press the steel ends against the roll ends with sufficient force to create a high frictional resistance to prevent the steel end from slipping or moving. ,: perpendicular to the blades in relation to the axis of rotation.

'·' | It should be noted that during the assembly process, the heated steel ends 40 of the hen are aligned with the roll ends 34 * t 25, wherein the plurality of bore holes 32 in the roll 30 are aligned with as many bore holes 54 as pass through the disks 48 and reinforcing plates. 44 through. The boreholes 54 terminate in recesses 56 which are larger in diameter than the boreholes 54 and include a narrow; · 30 truncated conical soles 58.

Conventional stress-generating devices include. threaded rods, tie rods, or cables inserted into aligned bore holes 54, 32. Conical beveled retaining clamps or clamping nuts: · 35 intended chucks are connected to the ends of conventional chords 113069 9 or cables. Conventional devices and techniques for tensioning steel ends (clamping or head-plates) on axial ends of roller bodies to cause axial tension in roller casings are described in U.S. Patent Nos. 4,642,862 and 4,272,873. Cover plate 66 may also be used in one embodiment of the invention. to cover the recesses 56. By tightening the tie rods or cables, the end 40 is secured to the end 34 of the press roll 30 and thus the opposing steel end becomes secured to the opposite roll end.

During the first stage of the roll assembly which includes the temperature of the ends 40 of heating a press roll to a higher temperature, the ends 40 extend radi-aalisessa 15 in the direction of arrow 60 as shown manner. The heated steel ends 40 are then secured to the ends 34 of the roll 30 with the boreholes 32 and 54 aligned. In the subsequent tightening step, the steel ends are pressed against the ends of the roll 30 as shown by the power arrows 62. As the steel ends subsequently cool, they shrink, and this shrinkage according to the arrows 64 targets ·, ·,: eliminates the radial compression force on the roll ends due to the high friction between the roll end surface 34 and the steel end surface 52. If the lip portion 50 and shoulder 38 have a tight fit, the lip portion 50 may shrink around shoulder 38 to slightly increase the radial compression area.

·. * Thus, the compression roller is subjected to radial compression at ambient temperature. Press roller hot

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: '; During use, the radial compressive force acting on it is gradually reduced as the steel ends expand in the radial direction at a velocity greater than .1 »due to the higher thermal expansion coefficient t of the steel end. Because the steel ends are heated to the full operating temperature; 35 ° C, there is virtually no outward radial net force caused by the thermal expansion of the steel end relative to the roll at operating temperature. In fact, by increasing the temperatures to which the steel ends are subjected to prior to assembly of the press roller assembly, the roll can be subjected to compression at operating temperature to further reduce the catastrophic damage caused by axial cracking due to circumferential tension of the press roll assembly.

10 It should be noted that high compression strength of granite rolls minimizes the risk that radial compression at ambient and operating temperatures would result in cracking or fracture of the roll, however, the low tensile strength of granite and related materials requires the avoidance of radial tensile stress. This object is clearly achieved by the present invention.

The improved press roll assembly of the present invention is very well suited for use in papermaking machines and the like. Although it is desirable to use granite: a solid cylindrical roll through which a plurality of ribs, ·,; diaphragm boreholes and related tendons, it is also possible to use the present invention. 25 lanes principle for preheated steel ends with rolls provided with central bore and '*' · longitudinally compressed by a single-V 'axial axis under tension pulling opposite steel ends of the roll | *: 30 per roll to maintain axial compression under the condition that the opposite steel ends are heated above operating temperature before the roll and steel ends are assembled.

Steel ends can be made of other high-strength materials in addition to steel, such as other metals and / or alloys, which may or may not contain iron. It is also possible that the method of the present invention, heating the steel ends before tightening them against the ends of a roll maintained at ambient temperature, can be used in conjunction with rolls having tapered ends and provided with steel ends having a compatible conical shape. In addition, the length, diameter, and weight of the roll being used, together with the roll roll end in use and other dimensions and shapes of the roll, may be varied, as will be apparent to one skilled in the art.

The number of tie rods or tendons in use will vary according to the length, size and weight of the roll in use and also depending on the bending stress under which the press roll is placed. The optimum amount and tension of the adjustable tie rods and the adjustment of the tractive force acting on them can be readily accomplished by one skilled in the art without unnecessary co-20 bowling.

Although the press assembly of the present invention may be readily prepared by one of ordinary skill in the art, as described above, to illustrate the invention, one non-limiting embodiment used in a papermaking machine will be described below. , where this compression roller assembly '' · has been used to replace a previously known roller which *. * * broke due to axial cracking.

Example 1 »» »:: 30 A granite roll with a diameter of 1500 mm and a length of 7 850 mm contained 30 longitudinal bore holes. with a diameter of 60 mm. These boreholes were placed, circumferentially of two concentric circles, at and radially to the end of the roll axis and around it.

; 35 Ten boreholes were placed in a 700mm diameter 113069 12 bolt but the remaining boreholes were placed in a circumference of 1,155mm diameter. The 30 tensioners were inserted into these drill holes and used to force the two steel ends towards each other to force the opposite ends of the 5 granite rolls, with the diameter of these steel ends at the point of contact with the roll ends.

The recommended source for granite rolls is ROCK OF AGES, located in Barre, Vermont, USA. The tendons 10 are preferably made from continuous threaded rods 35 mm in diameter, available from Dywidag Systems International, New Jersey, USA. (Note that other tendon structures, such as steel bars, cables, or the like, can be used to tension the steel-15 ends.)

The steel ends were preheated to approximately the operating temperature under which the press roll assembly was to be set, and these heated ends were tightened to the ends of the roll at ambient temperature. The complete 20 press roll assembly was then mounted on a papermaking machine where it was pressed against the other two rolls.

: The roll was designed to handle 12.5 kg / mm thread and 110 and 14.3 kg / mm thread at 330 ° (otherwise referred to as contact surface load, max or line pressure).

Other rollers of varying size and performance have been manufactured and installed on industrial machines without any observed axial cracking.

! : 30 Thus, although the present invention has been described; ; above, with reference to a preferred embodiment thereof, one skilled in the art can

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many different changes and variations. Thus, the embodiments described herein do not in any way: * 35 limit the present invention.

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Claims (20)

1. Pressure roller combination (30, 40) containing a roller (30) and ends (40), which ends (40) are formed of a material whose coefficient of thermal expansion is greater than the coefficient of thermal expansion of the material forming the roller (30). wherein the ends (40) place the roller (30) under radial pressure at ambient temperature to remove at least a portion of the tension tension of the roller (30) which arises upon heating of the roller (30) and the ends (40), characterized in that: the roller (30) is made of a substantially solid cylindrical body of stone material and with a first and a second end surface (34); and that the ends (40) attach to the end surfaces (34) of the roller (30) to form flat end faces. Combination according to claim 1, characterized in that the voltage present in the roller (30) is the peripheral voltage caused by the differential heat expansion of the roller (30) and the ends (40); wherein the peripheral voltage at the selected operating temperature. for the roller (30) and the ends (40) are approximately zero. , ·; 25 Combination according to Claim 1, characterized in that the roller (30) comprises a cylinder (30) having a first and a second opposing end (34), these gaps (34) being essentially flat, the ends (40) comprises two discs (48), whereby the discs (48) are forced against the gables (34) by means of a device which travels longitudinally of the roller (30). 4. A combination according to claim 1, characterized in! wherein the roller (30) comprises a cylinder having a first and a second opposing end (34), the gables (34) being substantially flat; the ends (40) comprise two discs (48) which are forced against the ends; and that the material forming the cylinder comprises granite and the material forming the discs (48) comprises steel. Combination according to claim 1, characterized in that the roller (30) comprises a cylinder with a first and a second end (34) which are substantially flat, the ends (40) comprising two discs (48), which by means of of friction is secured to the end members (34) by an axially directed force; each disk (48) further comprising a storage location (46) for rotating support of the ends. Combination according to claim 1, characterized in that the gift surfaces (34) are flat; and that the ends (40) comprise two discs (48) which are forced against these flat surfaces by an axially directed force; The discs (48) compressing the roll (30) radially at temperatures below a preset temperature. :. Combination according to claim 6, characterized in that it further comprises a plurality of axially rectified longitudinal drilling heels (32, 54) in the roller (30) and the discs (48); several longitudinal bore heels (32, ... 54) placed clamping devices (98) which join together the discs (48), these clamping devices (98) causing the skis (48) to be pressed against the ends of the roller (30) . Combination according to claim 7, characterized in that. the voltage present in the roller (30) is peripheral voltage caused by the differential thermal expansion of the roller (30) and the ends (40), this peripheral voltage at the selected operating temperature of the roller (30) and the ends (40) being about noli. Combination according to claim 8, characterized in that clamping devices (98) comprise adjusting rods or cables. Process for producing a press roll combination, characterized in that it comprises the following steps: heating two ends (40) to a first temperature, each end (40) having a substantially pianous contact surface; pressing and pouring said ends into the first temperature heated ends (40) against the opposing flat ends (34) of the cylindrical roller (30) at the corresponding flat contact surfaces, the temperature of the roller (30) being lower than the first temperature and its temperature expansion factor is less than the thermal expansion factor of the ends (40); and cooling the ends (40) to direct a radial compression toward the roller (30). 11. A method according to claim 10, characterized in that the ends (40) comprise metallic discs (48) and: the roller comprises stone material, the roller (30) and the discs. The holes (48) contain several rectified longitudinal drill shells (32, 54), wherein at least some of the drill heels (32, i, 54) in the discs (48) are aligned at least with some of the drill heels in the roller (30). ); wherein the pressing and pouring step comprises the following steps: placement of clamping devices (98) in at least in more aligned drill heels (32, 54); Ί attaching the opposite ends of the clamping devices (98) to the discs (48) for joining the discs (48); And forming a tension in the tensioning devices (98) to place the roller (30) under a longitudinal compression by means of a reaction directed against the discs (48). 5 Method according to claim 10, characterized in that the ends (40) comprise discs (48) which are coaxially disposed in relation to the roll (30), and that the roll (30) and these discs (48) contain several Aligned longitudinal bore heels (32, 54); wherein the pressing and pouring step comprises the following steps: placement of the longitudinal clamping devices (98) comprising first and second ends at least close to the aligned drilling heels; attaching the first and second ends of the clamping devices (98) to the discs (48); and providing a tension in the clamping means, such that the roller (30) is placed under longitudinal compression via the disks (48), the material of the roller (30) being granite and the disks material being stiff. '. '! 13. A method according to claim 10, characterized in that::: the clamping devices (98) comprise each clamping means, each of which has reaction devices j for attachment at the ends (40) and for directing one, force on them to force the ends (40) towards each other. 14. A method according to claim 10, characterized in that! »'; A first temperature is selected so that in the combination »there is essentially no peripheral voltage at ·; heating this combination to an operating temperature, which is approximately the same as the first temperature. 15. Pressure roller combination comprising a uniform cylindrical roller (30) provided with opposing axially flat ends (34), ends (40), which provide a flat contact surface (52) and which are positioned in -spective roller (30) each flat axial end (34) at the flat contact surfaces to form flat end interfaces, wherein several tensioned rods extend between the ends (40) and axially through the roller (30), the draw rods being positioned to pulling the ends (40) against the roller (30) to place the roller (30) under an axial tension, and the drawbars being located at a radial distance from the axis of the roller (30); characterized in that the ends (40) have been heated to a temperature which exceeds the rolling temperature and are not cooled to the rolling temperature before the ends (40) have been drawn towards the roller (30), the roller body being under radial compression at ambient temperatures, thus the at least part of the tensile stress caused by the heating of the press roll combination in the roller (30) is removed. Combination according to claim 15, characterized in that the axial planar gables (34) attach to the ends (40) along flat interfaces. 17. A combination according to claim 15, characterized in that the voltage in the roller (30) comprises a peripheral voltage caused by the differential thermal expansion of the roller (30) and the ends (40), this peripheral voltage * r * *. : 25 at the selected operating temperature is about zero. 18. A combination according to claim 17, characterized in that the roller (30) comprises granite and the ends (40). . 19. Pressure roller combination containing a roller, 30 (30), two metal ends (40), each having a hub portion (42) and a disk (48) integrally concentrically in the hub portion (42). , characterized in that the roll (30) is made of a substantially solid cylindrical stone material body which extends along and around the axis of rotation (36) and which has opposing flat round ends (34); Each disk (48) has a flat round surface (52) towards surface contact with the roll (30) corresponding to the flat round end (34); and that a plurality of radially extending clamping devices (98) are provided which are made of metal for joining and clamping the ends (40) to the roll (30), when the corresponding flat round surfaces (52) and the rollers (30) of the discs (48) flat round gables (34) star in mutual contact, each clamping device (98) extending through several longitudinally aligned heels (32, 54) formed at the ends (40) and roller (30) and through them, wherein the neck series (32, 54) is located on the side from the axis of rotation (36). Press roll combination according to claim 1, characterized in that each disc (48) contains a lip (50) extending circumferentially around the surface periphery of the disc (48) to define a round round recess (56) formed in the disc (48), and each flat round end (34) includes a shoulder (38) formed in the flat round end (34) and peripherally around its outer periphery to form a round plateau which is positioned • inside the shoulder (38), whereby the corresponding round plateaus and round recesses (56) are dimensioned for V · engagement with each other. * 14 1 · • · • · * f · * · '»» »